Mounting for articles



lJune 3, 1952 G. H. LEONARD 2,599,003

MOUNTING FOR ARTICLES Filed Oct. 16, 1947 3 Sheets-Sheet 1 ATTORN EYS June 3, 1952 H LEONARD 2,599,003

MOUNTING FOR ARTICLES Filed Oct. 16, 1947 3 Sheets-Sheet 2 ATTORNEY June 3, 1952 G. H. LEONARD MOUNTING FOR ARTICLES 3 Sheets-Sheet 3 Filed Oct. 16, 1947 A TTORNEYS Patented June 3, 1952 MOUNrING FOR ARTICLES George. H. Leonard, Noroton Heights, Conn., as-

sign'or. to Machlettv Laboratories: Incorporated.l Springdale, Conn-a corporation ofrGQnnotioail Yz ipx'izlieationfQstoiber 16, 194.47',` Serial', No4. '786,285 y claims. l(el. 24a-san This invention relates to mountings,v in which objects of various kinds may besupported, and is concerned more particularlyr with a novel mounting, which holds the object securely but permits its easy insertion and removal. Thienew mounting is especially adaptedv for supporting electronic tubes andy in that application, the mounting may include means forH cooling` the anode structure ofthe tube. Sucha form` of the mounting` Yalso includes packing. means. for. preventing escape of the cooling fluidalong the. tube and through the mounting, such means becoming effective automaticallyupon insertion. of; the tube in'the mounting. As. all of the` advantages of the invention. are. utilizedA in a form `of the.

newmounting for usewith electronicpower tubes and-'having anodecoolingmeans, suchan embodiment of the invention Will be illustrated. and described in detail forV purposesV of` explanation.

The. preferred: form ofv the. mounting. provided with anode cooling. means. includes a body have ingfan opening, through which theanode section of: the tube may be inserted. A chamber attached to the. body provides. an enclosure for the anode. and coolinguid maybe circulated through the. chamber arounditheanode. The bodyisprovided with. a circumferential seat within. the opening and: a. resilient packing ring. of toroidal. form is mounted within the body uponthe seat to encircle thev opening. The ring extends into., the path'of a part of the -anodesec'tion asthe latter. is inserted through the opening. and ring, and the ring is deiormed` by engagement with that part of the anode-section to increase its area of contact with the seat. Tubesof thepower type are frequently provided with a collar. adjacent the. inner end of the anode .section and, in order to prevent withdrawal of the tube from the mounting, the body is provided with means, which are movable to overlie. the collar orother part of the tube, when the tube is fully inserted in the mounting.

In one. formof thenew mounting, the circum.. ferential seat. within the body. extends parallel to the .axis of the opening and, in this construc-` tion, the: eiectiveness ofthe ring in making leakproof; contact with the body and the tube doesy not dependen axial clamping pressure'applied to the ring through a part of the tube. In that form ofthemounting, the mean-s for holding the tube in placeY in the mountingv is, accordingly, not utilizedr to apply pressure todeform the packing ring and.. merely' engages the collar or other prof jecting part ofthe tube, so as .to prevent the tube from being forced. out of; themounting.. by,4

in the mounting causes.. deformation. o the ring into incroas.ed-contact with the seat and, when the cooling fluid; under pressure is: admitted into; the chamber aroundthetube, thepressure maycause an outward movementv of thetube andtthiring. with. 'the latter distorted into., increased Contact. Withthe seat and. tube by .thelvpressure For a better understanding,v ofthe. invention, reference may be made to theA accompanying drawings, in which:

Fig, 1- is: a longitudinal sectional. view on the line I el. oIFig, 3 through one form4 of. thenew mounting;

Fig. 2. isa sectional View on the line 22 of; Fig. 4, showing. the mounting, with. a; tulzpe` in place therein;

Figs. 3 andY 4 are sectional views on thelines 3 3 of Fig. 1 and 4--4 of Fig. 2, respectixlze'ly;

Fig. 5` is a. fragmentary. sectionalv View on,y the line 5.,--5' of Fig. 6 showing. a modied; construe-f tion;

FFg, e is a too plan View of.` the mounting of.-

Fig. 7 isa fragrrientaryv longitudinal sectional, View showing. another mod-ined form of.` the mounting;

Fig. Sisa viewsimilantofFig. '7, showinga tube` l Fig. 13 is a View similar. toFig. 1,2 showing a tube inplaoo in the. mounting Fie- 1.4 is o fragmentary.- loneitndinolf seotionol viewshowinganother form of; the mounting; Fig, l5 is a view-similarto Fig. 1 4l showing when pnceinn1e-mounnno: Figs. 16 and` l'l-are fragmentary sootionolgnens. or another modified. formof thomonntnsfniih.

`collar I I.

a tube in place therein. the views showing the parts in different relations;

Fig. 18 is a fragmentary longitudinal sectional view of another form of the new mounting; and

Fig. 19 is a view similar to Fig. 18 showing a tube in place in the mounting.

The mounting shown in Figs. l and 2 is intended to be used with a power tube, which comprises an anode section I of generally cylindrical form. The tube has a collar II adjacent the inner end of the anode section and, beyond the collar, the tube includes a glass envelope I2 sealed to the enlarged inner end of the anode section.

One form of the new mounting for use with the tube described includes an annular body I3 having an internal iange I4, dening an opening of larger diameter than the anode section I0 of the tube but of less diameter than collar II. A chamber I5 extends from one end of the body in position to receive the anode section of the tube, when the tube has been inserted in the mounting with its collar resting on the shoulder I4a formed on the outer surface of the ange I4. At the outer side of the flange the body is formed with an internal channel c, the bottom of which forms a circumferential seat Ia. A packing ring I6 lies within the channel in contact with the seat.

The packing ring is of resilient material, such as a suitable rubber or synthetic rubber compound, and it is of toroidal form. The ring ordinarily is of circular cross-section, but, in some applications, a ring that is square or triangular in cross-section may be employed. The

bottom of the channel forms a circumferential seat against which the ring bears, and the ring projects inwardly into the opening through the body so as to lie in the path of a part of the anode section of the tube to be inserted in the mounting. In the construction shown, when the tube is being inserted in the mounting, the ,collar II engages the inner surface of the ring and causes the ring to be expanded and distorted, so as to increase its area of contact with the seat at the bottom of the channel. The width of the channel is greater than the greatest diameter of the ring, when so distorted, and ordinarily the ring does not make contact with the walls of the channel.

The end-of the body opposite to that from which chamber I5 extends, is formed with an internal channel, in which is seated a split retainer ring I'I. The ring is made of springy metal and, under normal conditions, it is seated tightly against the outer wall of the channel. The normal inner diameter of the retainer ring is sufiicient to permit the passage therethrough of The retainer ring is held in place by a cap plate I8 secured to the end of the body to overlie the ring by screws I9. A channel is formed in the face of the body along the outer edge of the latter beneath the cap plate and a locking ring is mounted in this channel. The locking ring extends outwardly beyond the outer surface of the body and its exposed edge is knurled, as indicated at 2l.

The inner edge of the locking ring is formed with a plurality of cam surfaces 22, and, opposite each cam surface, the top of the body is formed with a radial slot, in which lies a row of metal balls 23. The balls are in tight contact with one another and with the retainer ring I'I at one end of the row and with the cam surface 22 at the other end. At one end, each cam surface is provided with a notch 24, for a purpose to be described. The locking ring may be moved angularly with respect to the body of the mounting and such angular movement is limited by a pin 25, which is mounted in an opening in the top of the body and has a projecting end lying within an arcuate notch 26 in the inner edge of the locking ring.

The closed end of chamber I5 is provided with a threaded opening for reception of a pipe 2, through which cooling fluid may be introduced into the chamber. The fluid ows upwardly between the chamber wall and the tube and leaves through an opening in the side of body I3, into which an outlet pipe 28 is threaded. Opposite the outlet opening, the body is formed with an internal channel 29 to permit an increased flow of the fluid around the tube to the outlet.

In the use of the mounting, the locking ring is first moved to the position illustrated in Fig. 3, in which the deep portion of each cam groove lies opposite the end of the row of balls associated with that groove. In that position of the locking ring, the retainer ring II is fully expanded. The anode end of the tube is then inserted into the mounting and, when the collar I I enters the packing ring I6, it causes the latter to be distorted to make extended contact with the seat I5a at the bottom of the groove, in which the packing ring lies, and with the surface of the collar. The tightness of the contact of the packing ring with these surfaces does not depend on axial pressure applied to the tube but results from the pressure applied to the inner surface of the packing ring by the collar. After the tube is in position with the collar seated on flange I, the locking ring 20 is moved angularly to cause the cam surfaces to act through balls 23 to collapse the retainer ring, so that it overlies the end of the collar II. With the parts in the positions described, the tube is securely held in position and can only be withdrawn after the locking ring has been returned to the position illustrated in Fig. 3. When the locking ring has been moved to its extreme position for locking purposes, the outer balls in the rows enter the notches 24 at the ends of the cam surfaces and the seating of the balls in the notches prevents the locking ring from being shifted to open position by vibration. The tightness of the contact of the packing ring with the surfaces of its channel and with the surface of the collar is increased by the pressure of the iiuid, which may escape around the inner edge of the flange I4 into contact with the packing ring.

In the modified locking construction shown in Figs. 5 and 6, the locking ring 20 is formed with an inwardly projecting arm 3B, which lies in a cavity in the end of body I3 between stop surfaces 3I, 32, and extends into the space between the ends of the retainer ring I'I. When the locking ring 20' is moved to locking position, the inner end of arm 3U lies close to the ends of the retainer ring, so that, if the retainer ring should be corroded and adhere to the collar of the tube, the movement of the locking ring in clockwise direction to release the tube would cause the end of arm 30 to engage one end of the retainer ring I'I and break the adhesion of the ring to the tube.

In the modified construction shown in Figs. 7 to 9, inclusive, the body 33 of the mounting is formed with an inner wall 34 forming a circumferential seat, at the inner end of which is a flange 35. The body is formed with a plurality of radial openings, in which are mounted pins 36., each of which yhas a 'groove `on the under.` side of lits end exposed beyond the body. vAV ring 3.1. encircles the body. and isV supported "cna ring 38. seated in .a circumferential recess in the outer' surface. of .thebody .and projecting beyond Vthat surface. "Ring 3.7. is. provided with a 'plurality'of cams 66, which enter grooves in therespective plns36.

A packingring imr is mounted within the body,

against the seat 34 and the ring is of less.` internal i diameter than the cylindrical portion 4I. of vthe anode section ofthev tube..` When vthe anode section is' inserted through the body and ring, the -ring is distorted to increase its area ofvcon'f. tact Vwith the' seat `34 and'also vwith the inner. surface. 42 of-ange 35. When lthefcollar :on the tube. has .passed inward .beyond thepins 36, ring-3.1 may.' be moved angularly .and-:the cams thereonl thenV move the pins. 3,6-inward1y1 to over-v lie; the collar. The tube is then held against withdrawal Vand the distortion of the packing ring. into increased contact with seat 34. andthe inner surface 42. of ilange 3.5 by engagement off the anode section with the. inner. surface of :thejring insures a leakproof connection.

The 'construction shown in Eigs. l0 and 1l is somewhat similar to that. shown inFig. 7, except thatthetube isfcrmed with a collar 44. having a beveled section 45. As the tube is moved into themounting, rthe packing. ring 46. is engaged from within by the. beveled V.section 45 of the. collar. and forced into. increased. contact with the circumferential seat 41 on the inner. surfaceof thebody. andy also with the innersurface 4of flange 48 extending. transverse to. the axis oftl'leopen-- ing. through thebod-y.

.In the construction .shown in Figs. l2 and 13, thebodyisformedwith aninternal iiange 49., one face 49a of. which forms a circumferential seat encirclinggthe opening through which the anode end 50. of; the tube is to be inserted. A packing ring. .5J rests..uponseat Maand therirlgY hasV an internal. diameter, which. maybegreater thanY the diametenof. the anode. section .5.0 but is less,l than the outerdiameter .of the collar 52. of lthetube, 'lheouter surface. of the tube isv provided with threads 53, with which are engaged. thethreads, in the. interior. of av nut.. 5.4. The .nut is formed with a recess inward from the .threads1 .and a.. ringfwith'a cam surface. 56 isv mountedin the recess. A splitretainerring 51.- having a beveled surface. engagingthe cam surface 5.6 on rnf isjalso mounted, in therecess. Withv the een: struction. fdescribed, the tube is inserted in mounting. until` the. collarrests uponxthe top of. thepacking. ring .5l and the. top .of thecollar lies beneath the lower edge of .theretainer .ring 51. Nut 5.4 isnow turneduntil the camring` 5.5 moves downtoengage the end of the body. after which further turning of the nut causes. they locking. ring to be forced inwardly valong the camsuriace, 5,6.v The retainerring initially. moves inwardly to. overliethe upper end. of .collar .52.and-therer. after acts. through the collar to move` the. tube inwardly into 'the mounting, so. that the. collar4 deforms. the. packing ring .51. to give ,it increased.

areas .ofcontact with seat 46a 'and the under. surfaoeof collar52.

The construction shown in Figs. 1.4 and l5 1s employed-with 4a.V tube, vthe anode section -.5.8 ofVV which has a re-entrant portion at the. outer.. end offvvhich is mounted a'ring .59.. The. body 6.6. of the mounting has an opening `with an internal circumferential recess, thebottom.ofiwhichforms toroidal formrmayzbe. seated. .The packing `ring alsomakescontact with the inclined endrsurface 63.of'.ai ring 64., whichxlies within the. opening through the.body. and restsupon a spring 65 bear-.- ingagainst a. iiange 66 at .one end'of the body. Thewall 6l of the cooling chamber extends through the mountingandterminates it-68 withinthe `rte-"entrant portion of a tube in the mounting. .Acollapsible retainer ring 69 is mounted atthe end oi?v the. bodyl and is held in place by a cap :plate 10. A locking ring 1l. is mounted in the outer wall ofthev tube and has cam re-. cesses.. in .each of which. is mounted a hall 'I2 engaging the `outer:surface.. of the retainer ring, the Yarrangement beingv .generally similar` to that shownin Eig.. 3..

v.Upon insertionv of. tube. 58 in the. mounting shown in Figs. .14, 15, theccollar 5,9.. .0n the anode section of the tube makes contact with the packing ring 6.2; and, as the. tube is moved inwardly into the mounting. thev packing ring is distorted into increased contact with4 the seat Si and the sloping surface 6,3 of ring 6.4, which forms a second seat for. the ring. When the tube has been moved sufficiently far into the mounting, ring 7l. is moved angularly and balls 112 are cammedinwardly to. collapse the retaining ring 59, .until it overlies the outer surface of collar 5,9. The pressureof'the. cooling fluid, which may be introducedinto the chamber enclosing` the anodeend. .of the, tubein; any convenient manner, as, ifonexample, through an opening 1:3 in flange 66`.on. thefbody, insures that the packing ring willmakeftightcontact with. a seat 5l and with the inner end of collar 5.9..

Inthe constructionsshown in Figs. 116 and 17, theybody 14 of the mounting is formed with an internal flange. 'L5 and a. packing ring it nor mally rests upon the face of the flange and against a seat Tl `formed by the inner surface of. the body. The tube, has an anode section 1.3. o f less diameter than. the internal diameter of, ring I6 and. it is .also provided with a collar lwhich is of only slightly less diameter than the outer diameter of. the ring. The body is provided with locking. means, which are illustrated. as pins. 8.0, which may be independently operated oroperated simultaneouslyiby means of a locking ring, such as the locking ring 'H and balls. 12,'shown in lfig. 14. When a tube` is to berplaced inthemounting of Fig. 16;, its anode,

end is.` passed. through .the opening in theV body4 until the. .collar 1:9 on the. tube.. .rests upon the.

packing ringfl. Theretaining pins-.5.5 are then moved inwardly` to. overlie the upper surface of the. collar, 'Ehe :mounting is provided. with a cooling, chamber (not. shown) through which. cooling fluid under. pressure is circulated and, when. theotubeis, in place. in. the mounting and the uid admitted to. the. chamber, the pres,- sure of the.` fluid againstf the end of.. the.. anode sectionof the vtube. moves. the tube. outwardly.

witha plurality'of openings .8.3. A. pacliingring.

Mismounted within the .body to rest. on. the ,outer surface of. flange. v82.- and. theA body. isiprovided.

witlifretaining. meansin. theform. of. radial. vpins 9; seat slrgamstlwmch apackingring 6310i '(5 85. when; the tube .isinsertedin themounting.

7 the anode section 88 of the tube is passed through the opening defined by ilange 82, until the collar 81 on the anode section engages the packing ring 84 and distorts it into contact with the inner wall 82! of the body and into increased contact with flange 82. The pins 85 are then moved inwardly to overlie the outer face of the collar and the tube is then firmly held in place. The mounting is provided with a cooling chamber (not shown) receiving the anode section of the tube and, when cooling fluid under pressure is admitted into the chamber, it flows through the opening 83 in the flange and also around the inner edge of the flange to apply pressure to packing ring 85 and insure a leak-proof con tact of the ring with the circumferential seat S8 in the body and the inner surface of collar 8l.

Although a number of different forms of locking means for retaining the tube in the mounting have been shown, the constructions including a retaining ring and illustrated in Figs. 3, 6, and 14 are preferred for the following reasons. When the retainer ring Il, in the construction shown in Figs. 1 5, inclusive, for example, has been collapsed to overlie a part of the tube, such as the collar Il, and water has been admitted to the jacket, the pressure of the water against the tube causes collar Il to clamp the retainer ring I1 tightly against the under-surface of the cap plate I8. At this time, the outermost balls 23 in each row lie in their notches Zal in the locking ring 20 and, in order to release the retainer ring, the locking ring must be turned clockwise (as shown in Fig. 3). In the initial part of such movement of the locking ring, the balls are forced inwardly to permit the outermost ball in each row to move out of its notch 2li, and such inward movement of the balls causes a slight further collapse of the retainer ring. However, when the water pressure is applied to the tube, the collar Il clamps the retainer' ring Il so tightly against the under-side of the cap plate i8 that the locking ring can not be turned by hand. As a result, it is impossible to move the retainer ring to inoperative position while the water pressure is on and thus there is no possibility of discharge of water and accidental forceful expulsion of the tube from the mounting is prevented.

If, as a result of carelessness in locking the tube in the mounting, the locking ring is not moved until the outermost ball in each row is in its notch 24 and thereafter the water is turned on, it might be possible by application of considerable force to move the locking ring to release the retainer ring. However, the pressure of the water would cause the retainer ring to be clamped against the cap plate so tightly that the retainer ring could not expand and release the tube from its mounting.

Another advantage of using the retainer ring construction for holding the tube in its mounting is that the retainer ring makes a flat and substantially continuous contact throughout the entire circumference of the collar Il or a like part of the tube, when the tube is locked in the mounting. The pressure of the water against the tube is thus resisted throughout practically the entire circumference of collar Il and no points of stress develope on the collar with resultant possible distortion of the latter. Even a slight distortion of the collar may produce stresses, which are transmitted to the seal between the anode section and the glass envelope I2, and such stresses may result in leakage at the seal. With the construction described, the pressure applied to collar Il is approximately that of the internal water pressure only and, because of the distribution of that pressure continuously throughout substantially the circumference of the collar, the application of the Water pressure to the tube is not transmitted through localized areas of the collar to the metal-toglass seal with resultant damage thereto.

I claim:

l. A mounting for an article having an outwardly projecting circumferential collar spaced inwardly from. one end of the article, which comprises an annular body, a circumferential shoulder extending inwardly from the wall of 4the body in an opening through the body, the opening having an inner diameter larger than the outer diameter of the collar and the shoulder having an inner diameter greater than the outer diameter of said end of the article and less than that of the collar, an internal circumferential channel in the wall of the opening in the body between the shoulder and the outer end of the body, the bottom of the channel forming a circumferential seat, a resilient packing ring of toroidal form lying partially within the channel against the seat, the ring having a thickness less than the width of the seat and an internal diameter greater than the outer diameter of said end of the article and less than that of the collar. a resilient retainer ring mounted at the outer end of the body to surround the opening through the body, the ring being collapsible to overlie the collar of an article in the mounting, a locking ring mounted on the body for angular movement and encircling the retainer ring, and cam means operable by movement of the locking ring to collapse the retainer ring, the collar lying within the packing ring, when the collar is between the shoulder and the retainer ring.

2. A mounting for an article having an outwardly projecting circumferential collar spaced inwardly from one end of the article, which comprises an annular body, a circumferential shoulder extending inwardly from the wall of the body in an opening through the body, the opening having an inner diameter larger than the outer diameter of the collar and the shoulder having an inner diameter greater than the outer diameter of said end of the article and less than that of the collar, an internal circumferential channel in the wall of the opening in the body between the shoulder and the outer end of the body, the bottom of the channel forming a circumferential seat, a resilient packing ring of toroidal form lying partially within the channel against the seat, the ring having a thickness less than the width of the seat and an internal diameter greater than the outer diameter of said end of the article and less than that of the collar, a resilient split retainer ring mounted at the outer end of the body to surround the opening through the body, the ring being collapsible to overlie the collar of an article ln the mounting, a locking ring mounted on the body for angulaimovement and encircling the retainer ring, means on the body for limiting the movement of the locking ring and the angular displacement of the retainer ring, and cam means operable by movement of the locking ring to collapse the retainer ring, the collar lying within the packing ring, when the collar is between the shoulder and the retainer ring.

3. A mounting for an article having an outwardly projecting circumferential collar spaced inwardly from one end of the article, which com.- prses an annular body, a circumferential shoulder extending inwardly from the wall of the body in an opening through the body, the opening having an inner diameter larger than the outer diameter of the collar and the shoulder having an inner diameter greater than the outer diameter of said end of the article and less than that of' the collar, an internal circumferential channel in the wall of the opening in the body between the shoulder and the outer end of the body, the bottom of the channel forming a circumferential seat, a resilient packing ring of toroidal form lying partially within the channel against the seat, the ring having a thickness less than the width of the seat and an internal diameter greater than the outer diameter of said end of the article and less than that of the collar, a resilient split retainer ring mounted at the outer end of the body to surround the opening through the body, the ring being collapsible to overlie the collar of an article in the mounting, a locking ring mounted on the body for angular movement and encircling the retainer ring, the locking ring having a projection lying between the ends of the retainer ring, and cam means operable by movement of the locking ring to collapse the retainer ring, the collar lying within the packing ring, when the collar is between the shoulder and the retainer ring.

4. A mounting for an article having an outwardly projecting circumferential collarspaced inwardly from one end of the article, which mounting comprises an annular body having an inner diameter larger than the outer diameter of the collar, a circumferential shoulder extending inwardly from the wall of the body in the opening through the body, said shoulder having an inner diameter greater than the outer diameter of said end of the article and less than that of the collar, an internal circumferential channel in the Wall of the opening in the body between the shoulder and the outer end of the body, the bottom of the channel forming a circumferential seat, a, resilient packing ring of torodial form lying partially Within the channel against the seat, the ring having an internal diameter greater than the outer diameter of said end of the article and less than that of the collar and a thickness less than the width of the seat which thickness is of the same order of magnitude as the axial length of the collar, and means at the outer end of the body for preventing removal of the article from the body, said means including an element movable radially to overlie the collar of the article, the collar lying within the packing ring, when the collar is between the shoulder and 10 the movable element, the packing ring forming a fluid-tight seal between the circumferential seat and the collar, the means for preventing removal of the article from the body being independent of the means for making said Huid-tight seal.

5. A mounting for an article having an outwardly projecting circumferential collar spaced inwardly from one end of the article, which mounting comprises an annular body having an inner diameter larger than the outer diameter of the collar, a circumferential shoulder extending inwardly from the wall of the body in the opening through the body, said shoulder having an inner diameter greater than the outer diameter of said end of the article and less than that of the collar, an internal circumferential channel in the wall of the opening in the body between the shoulder and the outer end of the body, the bottom of the channel forming a circumferential seat, a resilient packing ring of torodial form lying partially within the channel against the seat, the ring having an internal diameter greater than the outer diameter of the said end of the article and less than that of the collar and a thickness less than the width of the seat, which thickness is of the same order of magnitude as the axial length of the collar, means for preventing removal of the article from the body including a resilient retainer ring mounted at the outer end of the body to surround the opening through the body and collapsible to overlie the collar of an article in the mounting. and cam means for collapsing the retainer ring, the collar lying within the packing ring, when the collar is between the shoulder and the movable element, the packing ring forming a fluidtight seal between the circumferential seat and the collar, the means for preventing removal of the article from the body being independent of the means for making said fluid-tight seal.

GEORGE H. LEONARD.

REFERENCE S CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,137,085 Riddle Apr. 27, 1915 1,571,948 Housekeeper Feb. 9, 1926 1,700,478 Haddock Jan. 29, 1929 1,735,816 Trogner Nov. 12, 1929 1,814,376 Gebhard July 14, 1931 1,864,963 Vadersen June 28, 1932 2,187,217 Winslow Jan. 16, 1940 2,470,419 Voytech May 17, 1949 

